@ McLovin'

About the Xion matter, in the universe of Kingdom Hearts, memories aren't actually what you and me would think of a memory. In Kingdom Hearts it's something more trivial, so to say.

You may imagine each memory as some kind of a picture, which, once in your body, can't ever be removed again.
These pictures are tied together, each very single memory. And furtherly (As I interpret it) these tied memories also tie to your soul.
So there's basically some kind of chain of memories inside one in Kingdom Hearts.

Once a memory isn't actually tied to the chain, the memory's owner won't remember the memory's happenings, but the memory itself won't be gone but only untied.


I think this is what Xion meant; they will forget her (their memories will become untied) but the memories will always be there (as explained above).